Will he not make some suggestions of his own? Or give you any sort of guidance as to what might appeal to him, or reasons for vetoing every name you suggest? It seems like he ought to either actually contribute to the decision, or let you make it on your own and accept whatever you choose.

Have you considered using Mae as the first name, since I assume he agreed to using it in the middle spot? Unless that is too painful or awkward with the recent loss of the loved one you intend to honor.

Other ideas (sorry for repeats from your veto list, it's a long one!)...